• 한국시스템다이내믹스연구
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• 제4권2호
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• pp.95-130
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• 2003

The purpose of this study is to find what causes make public projects hold off, going beyond the planned deadline and budget. Using System Dynamics(SD) and their derivative Urban Dynamics(UD) models, it intends to analyze major feedback loops based on VENSIM and to simulate them with STELLA software, all of which are interrelated with various causes of project delay. To prevent or ameliorate project delay, first of all it advises to focus on endogenous delaying factors not exogenous ones. These factors either reinforce or balance certain loops in complex causal structure, In the case example on the Cremation Building Project in Cheongju, Residents’ participation demand make negotiation put off and delayed negotiation reinforces administrative-expediency planning in order to observe a time limit, on the other hand, once building consensus, it increase both the level of planning performance and public trust. In the meantime, the real planning process used to neglect residents opinions and manage public grievance only through compensation, he a result of simulation, visible fruit of negotiation in the initial phase seems to be not satisfactory owing to funds and time consumed, but after reaching an mutual agreement among stakeholders, planning performance is effective and strategic than administrative-expediency planning viewed in both financial and time angle. It proposes to devise specific tools schematizing project implementation. In order to upgrade the quality of project management, it recommends for planners to adopt key concepts based on SD/UD diagrams and causal loops, which would contribute to enriching Planning abbots.

• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.66-74
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• 2007

We have developed a multi-channel, multi-frequency EIT system with operating frequency of 10Hz to 500KHz. The number of digital voltmeters using phase-sensitive demodulation can be varied from 8 to 64 and we found that 16 and 32-channels are most practical. This paper describes the design, implementation, and construction of 16 and 32-channel systems. The performance of the system was thoroughly tested and we found that CMRR of the developed voltmeter is about 85dB with $100{\Omega}$ unbalancing series resistor. The SNR is greater than 99.6dB and the output impedance of the constant current source is $1{\Omega}W$ at least for all frequencies. Imaging experiments using a banana with frequency-dependent conductivity and permittivity show that frequency-difference imaging is possible using the developed system. Future works of animal and human experiments are discussed.

• Journal of Electrical Engineering and Technology
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• 제3권1호
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• pp.79-87
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• 2008

This paper proposes the design and implementation of a direct torque controlled induction motor drive system. The method is based on control of decoupling between amplitude and angle of reference stator flux for determining reference stator voltage vector in generating PWM output voltage for induction motors. The objective is to reduce electromagnetic torque ripple and stator flux droop which result in a decrease in current distortion in steady state condition. In addition, the proposed technique provides simplicity of a control system. The direct torque control is based on the relationship between instantaneous slip angular frequency and rotor angular frequency in adjustment of the reference stator flux angle. The amplitude of the reference stator flux is always kept constant at rated value. Experimental results are illustrated in this paper confirming the capability of the proposed system in regards to such issues as torque and stator flux response, stator phase current distortion both in dynamic and steady state with load variation, and low speed operation.

• 한국콘텐츠학회논문지
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• 제14권2호
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• pp.223-233
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• 2014

정책과정에의 참여자로서 주민들의 역할은 매우 크며, 특히 민주주의의 구현을 위한 중요한 장치의 하나로써 인식되고 있다. 우리나라에서도 지방자치제도가 안정화 단계에 들어서면서 예전에 비해 여러 가지 지자체의 시책이나 중앙정부의 정책결정과정에 관심이 매우 높아졌다. 그렇다면 실제 정책결정과정에서 지역주민들의 참여가 활발할까? 하는 질문으로 본 연구는 출발하였다. 특히 본 연구에서는 지역불균형 문제와 관련하여 해소 방법의 하나로 인식되고 있는 공공기관 이전결정과 관련하여 해당지역주민들의 참여의사를 측정하고 의미 있는 결과를 도출하였으며, 이러한 연구결과를 바탕으로 지역주민의 정책결정에의 참여에 있어서의 시사점을 논의하였다.

• Journal of Biosystems Engineering
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• 제27권3호
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• pp.203-210
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• 2002

In this study, the leveling control system for a tractor has been developed. The experimental model showed that the implementation of the proposed hydraulic control system fur the prototype design of a slope land tractor was feasible. The front axle was designed as a center pin type and the rear axle was designed as a trailing arm type. The leveling control of the body on the slope land was accomplished by controlling the height of the right and left trailing arms using the electronic controlled hydraulic cylinder. The maximum leveling control angles were ${\pm}$15$^{\circ}$ for roll angle and 7$^{\circ}$far pitch angle. The front and rear wheel drives were transmitted by gears from the main shaft to the final drive. The adaptability of the hydraulic control system was tested and investigated by analyzing the system response in time and frequency domain. The hydraulic control system on a step input showed a linearly increasing trend without any overshoot state. The hydraulic control system on a frequency input showed a little phase differences and gain drops within the range of 0.3Hz.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2000년도 정기총회 및 학술대회
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• pp.43-48
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• 2000

본 논문에서는 디지털 오디오 방송 시스템으로서 사용하기 위한 AAC (MPEG-2 Advanced Audio Coding) 코덱 시스템의 개발에 관하여 기술한다. 인코더 및 디코더는 ETRI가 제안한 디지털 오디오 방송 시스템에 접속하기 위해 MPEG-2 (Moving Picture Experts Group phase 2) 시스템의 TS(Transport Stream) 형식으로 입/출력한다. 내부 오디오 신호처리를 위한 DSP(Digital Signal Processor)로서는 Tl(Texas Instruments) 사의 TMS320C6701 (Floating point, 166 MHz)을 사용하였다. 인코더에서는 DSP 를 4 개까지, 디코더에서는 3 개까지 사용하여 구성할 수 있도록 설계하였다. DSP 에서는 시스템 제어, 오디오 신호 입력, 오디오 신호 처리, TS 신호 발생, 비트스트림 출력 등의 처리를 수행하며, 각 DSP 는 직렬 및 병렬 접속에 의해 서로 데이터를 전달한다. 본 시스템은 이후 다양한 디지털 방송 분야에 활용될 것이다.

• 정신신체의학
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• 제1권1호
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• pp.14-24
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• 1993

The author discussed present problems and future prospects of psychosomatic medicine in clinical, educational, research, and social aspects. In general, psychosomatic field. particularly. consultation-liaison(C-L) psychiatry in Korea seems to remain on early developmental phase. However, positive change in the general publics' and societal view of psychiatry, specialization of medicine and development of medical technology, implementation of delivery system in medical care could contribute to development of this field. In future, clinically, liaison activity will be more activated. and this field will be developed as main subspecialty of psychiatry. In addition. C-L psychiatry will be subspecialized. and prevention and humanization of medical care could be more emphasized. In education. the main place of education for medical students and psychiatric residents will be changed from closed ward to general ward in which consultation-liaison activity can be performed. In research. consultation liaison model suitable for Koreans will be developed and studies on disease mechanism will be more promoted. In social aspects, this field could influence the general publics' view of psychiatry and change the whole areas of medicine and society toward integration. In order to achieve these goals, medical insurance system and cost relevant to C-L activity should be essentially improved.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2008년도 추계학술대회 및 정기총회
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• pp.455-459
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• 2008

This study defines the Next Generation System(NGS) built by domestic financial businesses and classifies their architecture into two typical types according to the duration of the project and the relative cost of IT investment in the short term: the Big Bang approach and the Phase approach. Herein, we study the two approaches as alternatives in developing the Next Generation System, and derive the factors that are to be considered in the evaluation of the two alternatives for financial businesses. The set of standards for the choice between the two models are grouped into categories that constitute performance evaluation for IT - Cost, Performance and Risk. We drill down further into each category to second and third subordinate levels to derive detailed selection criteria. Based on the criteria drawn from the study, we conduct a survey with information system planners, IT managers and specialists at financial companies who are currently planning, developing or have completed a Next Generation System. Survey results are analyzed using the AHP methodology to compare and understand the different approach in the implementation of NGS for financial business.

• 한국컴퓨터산업학회논문지
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• 제2권11호
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• pp.1373-1382
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• 2001

이동통신 텔레트래픽 모델은 Network Traffic 모델과 Traffic Source 모델이라는 두 개의 하부모델로 구성된다. 본 논문에서는 기지국이 설치되어 있는 지역 특성을 고려한 traffic source 모델을 제시하고, 이동통신 트래픽 시뮬레이터인 MobCall을 구현하였다. MobCall은 사용자 이동성을 각 지역별 차량 평균 속도와 수송분담율을 적용하고 있다. 구현된 MobCall을 이용하여 서울 도심 주거지역과 상업지역에서의 누적 발생 호 수, 교통량에 따른 핸드오프 율, 고속도로에서의 핸드오프 율, 그리고 호 점유 시간 변화에 따른 핸드오프 율을 결과로 제시하였다. MobCall은 기지국에서 사용자 호 패턴에 따른 동적 핸드오프 버퍼링과 같은 기능적 요소를 설계 단계에서 고려할 수 있다.

• 한국정보통신학회논문지
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• 제5권1호
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• pp.202-211
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• 2001

본 논문은 수중에서 초음파를 이용하여 데이터를 전송할 때 전체 전송성능에 영향을 주는 Multipath를 수학적으로 분석하였고, 분석된 결과를 이용하여 다중경로의 영향을 고려한 수중 초음파 영상통신 시스템을 설계하였다. 주파수 제약환경에 강인한$\pi/4 QPSK$ 알고리듬을 채택하였고, 수중 초음파 통신에서 발생하는 신호의 Ringing 효과를 상쇄하기 위하여 FM 변조방식을 가미한 Hybrid 변복조 시스템을 설계하였다. 또한, 다중경로의 영향을 상쇄하기 위하여 적응 등화기를 설계하였으며, Baseline PEG 기법을 이용하여 수중영상 압축에 대한 연구를 수행하였다.